Bulgarian authorities said Tuesday they have detained the owner of the Rhosus, the ship that transported the deadly cargo of ammonium nitrate to Beirut in 2013, in a move that could inject new momentum into the stalled probe of the 2020 port explosion.

A spokesperson for Sofia City Court confirmed the arrest of the ship’s owner, who is wanted in connection with the investigation into the blast that leveled swathes of the Lebanese capital on August 4, 2020. The court will place him in custody for up to 40 days under a ruling issued on September 7, later upheld on appeal, according to the spokesperson.

The surprise development comes more than five years after the blast, which killed more than 200 people, injured thousands, and devastated entire neighborhoods in Beirut. The suspect, who had remained out of public sight for years, is viewed by investigators and rights advocates as a central figure in bringing the deadly shipment to Lebanon.

Initial reports suggest the arrest was carried out under an Interpol red notice issued at the request of Lebanese judicial authorities. The man, described as a businessman with key involvement in transporting the hazardous cargo, could face extradition proceedings to Lebanon.

Legal experts say the detention could open the door to renewed inquiries into how 2,750 tons of ammonium nitrate ended up abandoned in unsafe storage at Beirut’s port, ultimately triggering one of the largest non-nuclear explosions in history.

Lebanese authorities are now expected to launch extradition procedures, though legal and political obstacles have long hampered progress in the case.